Method of and apparatus for renewing oil wells



Dec. 11 1923. 1,476,747

F. H. WDL-EVER METHOD OF AND APPARATUS FOR RENEWlNG OIL WELLS Filed Jan.2. 1920 5 Sheets-Sheet 1 Fgi. E?

Dec. 11., 1923. Y

F. H. WOLEVER METHOD OF AND APPARATUS FOR RENEWINQ OIL WELLS Filed J an.2. '1920 5 Sheets-Sheet 2 7 INVENT R Fizz/M ?[[7////L 6/" A TTOHWEY Dec.11, 1923.

F. H. WOLEVER METHOD OF AND APPARATUS FOR RENEWING OIL WELLS 5Sheets-Sheet 5 6/ Filed Jan. 2,

Dec. 11 ,1923.

F. WOLEVER METHOD OF AND APPARATUS FOR RENEWING OIL WELLS Filed Jan. 2,1920 5 Sheets-Sheet 4 Dec. 11 1923.

F. H. WOLEVER METHOD OF AND APPARATUb FOR RENEWING OIL WELLS Filed Jan.2. 1920 5 Sheets+-Sheet 5 i W w Z 7 81 m mm M L Patented Dec. 11, 1923.

UNITED STATES FRANKLIN H. WOLEVER, OF CHICAGO, ILLINOIS.

METHOD OF AND APPARATUS FOR RENEWINGOIL WELLS.

Application filed January 2, 1920. Serial No. 348,949.

T 0 all whom it may concern:

Be it known that I, F RANKLIN H. WoLE- van, a citizen of the UnitedStates, and a resident of Chicago, in the county of Cook and State ofIllinois, have invented certain new and useful Improvements in Methodsof and Apparatus for Renewing Oil Wells; and I do hereby declare thatthe following is a full, clear, and exact description thereof, referencebeing had to the accompanying drawings, and to the characters ofreference marked thereon, which form a part of this specification.

This invention relates to a novel method of and apparatus for renewingoil wells which have been clogged by compacted sand mixed withhydrocarbon constituents of petroleum oil, such as shale, parafiin,bitumen, and other mineral binders, and refers to a method to removefrom the casing and the area surrounding the same such clogging depositsto permit a free flow through the casing screen within the casing, andrelates also to a novel apparatus for practicing the method. It has beenfound in practice that sand, mingled with the mineral hydrocarbon, waxyconstituents of the oil, such as paraflin, bitumen, and the like, packsin a very solid mass Within and exterior to the casing in a manner toobstruct the oil flow, and heretofore it has been a practice to shootthe well to break up this mass. Such operations are attended withvarying, and usually small, success. r

In accordance with the present method, it is proposed to deliver to theobstructing, packed sand deposit a solvent of such nature as willv actupon and dissolve the binderwhich holds the sand particles together andto a itate this dissolved mass in such a way in t e presence of thesolvent and in the presence of air so that the specific gravity of themass will be lowered to such extent that the commingled sand, fluid, andair may bereadily raised to the level of the top of the well anddischarge therefrom, this operation continuing until all of the sand hasbeen removed. The solvent used is preferably of a character which isneutral to the material of the mechanism by which the sand is agitated.Carbon tetra chloride mixed with gasoline in proper proportions is sucha solvent agent, and by reason of its heavier specific gravity may beemployed in wells containing more or less water. In some cases where thepacked sand forms some distance around the casing, it may be desirableto remove the entire mechanism from the well and thereafter deliver astrong solvent of such character as will dissolve the sand itself andthen remove the mixture from the well.

After the sand has been removed and no trace of oil appears, or shouldwater be found to flow for some lon period of time through the bottom oft ecasing, it is generally known that the well is not pro ductive.

The principal novelty of the present method resides in the means fordelivering the solvent to the bottom of thecasing, excavating the packedsand and agitating it in and mixing it with the solvent so as todissolve the binder and to thereby decrease the specific gravity of thesolution mass so as to enable it to be raised to the top of the well, asby means of a suitable pump, or otherwise. i

The mechanism for practicing the process embraces an operating head orunit which is lowered to the bottom of the casing, abreast the casingscreen, and it embraces in its construction, in general terms, asuitable excavator, a motor for driving the excavator, such as an air,steam, water, or electric motor, a device for mixing the solvent withthe loosened sand, and a lifting pump into which the mass of commingledsolvent and sand is discharged and by which the mass is raised, theraising of the mass being assisted by the exhaust motive fluid from themotor which operates the entire unit, when such a motor fluid as steam,air, or water is used.

Auxiliary features of the invention reside in means at the top of thewell for circulating the sol-vent fluid through pipes that are connectedto the head of the operating unit at the bottom of the casing so as tomaintain a continuous flow of the fluid through the head,.and thecircuit through which the solvent flows is preferably associated withmeans to separate the sand from the fluid mixture raised from the wellso that the solvent fluid may be used over and over again.

In the following description it is assumed that the operating head isdriven by air, and for sake of clearness of description correspondingterminology will be employed, but it is understood that said terminologyis not intended to limit me with respect to the. motive power.

As shown in the drawings; I

Figure 1 illustrates the manner in which the device is inserted into thewell, with the operating unit abreast the oil bearing sand stratum, andwith the solvent circulating mechanism and compressed air deliveringmechanism at the top of the well.

Figure 2 is a side elevation of a motor carried derrick for initiallylowering the device into the well.

Figure 3 is an enlarged axial sectional view of the operating head atthe bottom of the casing, showing the perforated casing section andillustrating the screen therearound.

Figure 4 is a side elevation of the head.

Figure 5 is a cross section on the line 55 of Figure 3.

Figure 6 is a cross section on the of Figure 17.

Figure 7 is a cross section on the line 77 of Figure 3. a

Figure 8 is a cross section on the line 8-8 of Figure 3.

Figure 9 is a cross section on the line 9-9 of Figure 10.

Figure 10 is a detail of the joints for connecting the sections of thepipes for the circulating solvent fluid and the motive'agent.

Figure 11 illustrates a modified cross over joint hereinafter to bedescribed.

Figure 12 is a section on the line 12-12 of Figure 3, looking upwardly.

Figure 13 is a detail of the excavator at the lower end of the operatinghead or unit.

, Figures 14 and 15 are vertical sections of the lifting pump on thelines 1414, 1515, respectively, of Figure 5.

Figure 16 is a detail of the lifting pump hereinafter described.

Figure 17 is a fragmentary vertical section illustrating the manner ofbringing the solvent and motive agent's out of the top of the well, andthe manner of controlling the rise and fall of the operating head orunit to control its attack on the sand.

Figure 18 illustrates one form of settling device by which the sand maybe settled out of the solvent fluid so that the latter may be used overand over.

Figure 19 is a detail of a shackle hereafter described.

Figures 20 and 21 are details of the long and short pipe sections of thefluid solvent and motive agent circulating pipes.

Referring, first, to Figures 3 to 16, incluline 66 sive, whichillustrates the operating unit or head at the bottom of the casing,.l5designates the usual casing which is perforated at its bottom and issurrounded by a screen sage of water into the shell from the casingexterior to the head.

At the bottom of the unit is located an excavator designated as a wholeby 26. It is shown as a four blade spiral excavator, with two longspiral blades 27 and two shorter spiral blades 28, herein shown aslocated beneath the blades 27, and said excavator terminates below theshorter blades 28 in a cutting point 29. Said excavator is fixed to ashaft .30 (Figure 3) that is rotatably mounted in a bearing 31 near thelower end of the operating unit 18. The shaft also carries just abovethe excavator a hollow multi-blade centrifugal-pump 32 (Figures 3 and8). Said bearing is formed in the lower section 33 of the shell that isfixed to the section 21 by the screws 34. The said bearin 31 is formedwith a stufiing box 31 (Figure 3) to prevent leakage of water into theshell around the shaft 30.

The shaft 30 carries at its upper end an internally toothed gear 36 thatmeshes with a pinion 37 that is carried by the lower end of a shaft-38which is rotatably mounted in a suitablebearing 39 fixed by the studs 39(Figure 4) to the section 21 of the shell 18. To the upper end of theshaft 38 is fixed a second internal spur gear 40 with which meshes apinion 41 that is carried by the lower end of a shaft 42 which ismounted in a suitable bearing 43 fixed to the section 21 of shell 18 andis equipped with a step bearing 43.

45 designates as a whole a motor which, as herein shown, is a threestage air motor operated by compressed air. It comprises the three setsof spiral blades 46, 47, 48, and fixed blades 49, 50. While a threestage turbine motor is herein. shown, it will be understood that anyother suitable form of motor of sufficiently high velocity may beemployed, and, furthermore, that the special design of the motor and themanner of mounting it in the shell may be varied.

52 designates a spirally bladed lifting pump that is located in asuitable casing 53 above the motor 45, and the shaft 54 of said pump isdirectly connected to theshaft of the turbine 45. In Figure 5 isillustrated the neral arrangement of the blades 55 of the ifting pumpand of the casing 53 thereof. The pu1np casing is provided with an inletopening 56 shown best in Figure 14 and with an outlet opening 57 bestshown in Figure 15..

The section 19 of the shell 18 of the operating head or unit is providedat its top with openings to receive four pipesv 60, 61, 62, 63, theformer two of which respectively constitute the solvent solution supplyand solution discharge pipe, and the latter two of which respectivelyconstitute the motive agent supply pipe and motive agent discharge pipe.The said pipes extend from the operating head upwardly through the wellcasing and are connected at suitably spaced points by coupling discs ormembers 65, shown best in Figures6 and 10, and other coupling members 65shown best in Figure 11, the ends of said pipe sections being threadedto enter through registering connecting opening 65 of the couplingdiscs. The discs are held in proper register, as by a stud 65 ofone discentering an aligned socket in the other disc, indicated in 1 Figures 9and 10. Some of said discs are externally threaded to engage hollowcoupling sleeve 66, each of which is shouldered at 67 to engage over anupper coupling disc of a pair and is threaded at its other end to engagethe threads of the lower coupling disc of said pair. The lower disc ofeach pair has a threaded socket 65 in which there is introduced across-over r the center of the coupling where the crossover conduit orchannel is equipped with a check valve 65 that closes towards thepassage 65 which is in communication with the air discharge pipe. I

The cross-over coupling will alternate with the couplings shown inFigure 10 in such a way as to locate the cross-over couplings at properstages or levels to introduce air under pressure from the air dischargeor supply pipe, to the fluid discharge pipe to thereby relay or boostthe lifting effect of the centrifugal pump 52 at proper stages and atproper times, and thus aid in lifting the solution of mixed solventsand, and air. Fluid pressure on the check valve 65 normally holds thevalve seated, and when air is to be forced throughthe crossover aircouplings, into the fluid discharge pipe 61, the air discharge pipe maybe throttled by a suitable valve 63 (Figures 1 and 17) or the pressurein the air supply increased until pressure therein is suflicient to liftthe valve 65, as hereinafter more fully described.

The solvent solution is supplied to the operating unit or head 18through the pipe 60 which connects with a nipple 68 (Figures 3 and 4) atthe upper end ofthe head casing. Said nipple communicates with avertical passage 69 that leads downwardly inside the casing and isprovided at its lower end with an internal nozzl 70 which directs thesolvent into the centrifugal pump 32. The pipe 61 communicates with theoutlet or discharge passage 61*, of the lifting pump 52. The pipe 62 isa supply pipe for the motive agent, and directs the motive agent. asair, steam, Water, or the like, to the turbine motor 45,

' said pipe being threaded to a nipple 72 that communicates withachannel 73, the nozzle discharge pipe 61. Said pipe 61 discharges onto aplate 89 of the settling chamber, and the sand and solids of the mixturecollect in the bottom of the chamber (Figure 18). The pipe 60 leads fromthe tank 80 at a point above the bottom thereof to draw clean solventsolution therefrom. The air supply pipe 62 is connected to an air tanksupplied with compressed air from an air compressor 85 on the motortruck through the medium of a pipe 86. The air outlet pipe 63 from theturbine motor discharges to the atmosphere, as shown in Figure 1, and isshown as provided at its upper end with a throttle valve 63'.

Preferably the operating unit or head 18 and its connecting pipesections, comprising the pipes 60 to 63, inclusive, are slowlyreciprocated during the rotation of the excavator 26 so as to cause theexcavator to more efficiently attack the hardened sand. The operatinghead and connected pipes are raised by a piston 99 in a cylinder 100(Figures 1 and 17), the piston being connected by the stem 101 to anupper coupling 101, to which the upper ends of the pipes 60, 61, 62, 63at, the top of the well are connected in the manner shown in Figure 17.The cylinder 100 is supported on a stand 102 at the top of the well. Thepiston 99 is lifted in said cylinder by air delivered to the cylinderthrough a branch 62 of pipe; 62, a

' mining the rate of speed of the flow of air controlling Valve 103being placed between branch 62 and the bottom of the cylinder 100. Arestricting valve 104 is interposed between the branch ,pipe 62 and thecontrolling valve 103, and a like restricting valve 105 discharges fromsaid controlling valve 103 to the atmosphere. These restricting valvesdetermine the speed of travel of the piston 99 in the cylinder 100 andof reciprocation of the operating head by deterto and from the cylinder.

The controlling valve 103 is operated to alternately connect thecylinder to branch pipe 62 and to the atmosphere by a valve ping collars110 on the piston stem 101, me-

tion being communicated from the trip lever to therocker through pins112 on the rocker.

The construction of the separator is shown in Figure 18. The solventfluid discharges from the pipe 61' directly on a distributing orspreader plate 89 from whenceit falls into the bottom of chamber 83where the heavy sand, et cetera, settles. The clean fluid is drawn offfrom settling tank through pipe 84 that discharges into the pipe 60. Aglass 92 is placed across the swinging cap 93 of the separator andenables the character of the material discharged on the plate 89 to beobserved.

In the operation of the device, air, at suitably high pressure, isdelivered through the pipe 62 to the turbine motor 45. The power of saidmotor is communicated through the pinions 41, 37, and gears 40, 36, totheshaft 30 of the excavator 26 and centrifugal pump 32. The excavatorserves to loosen the body of sand within the bottom of the casing andthe solvent material is directed from the pipe through the channel 69and its nozzle 70 centrally to the centrifugal pump 32. By the action'ofsaid pump, rotated at a speed lower than the turbine 45 due to the gearratio between them, the solvent is thrown outwardly against and downinto the loose sand and binder material broken up by the excavator 26.The binder in the sand is dissolved by the solvent material, so that themixture rises through the annular passage 95 between the well casing andthe shell 18. This solvent material is delivered through the inletpassage 56 (Figure 14) to the spirally bladed lifting pump 52, whichforces the liquid upwardly through the pipe 61 and into the top of thefilter. The mass of solvent laden material is lightened by air from thedischarge pipe 63. The circulation of said solvent thus freed from thesand is established through the circuit comprising the pipes 60, 61, andthe proper passages in the operating head unit so that when thesand andheavy materials are thus settled out of the solvent, the relativelyclean solvent fluid may be used over and over again, it being circulatedin the closed circuit thus alt'orded. If desired, the solvent materialmay be directed to the operating unit and afterwards discharged togetherwith the sand therein to a sump. Theprovision, however, for settling thesolids from the solution and using the clean solvent over and over againis preferred by reason of economy.

The attack of the solvent on the sand is not necessarily limited to hearea within the well casing but may extend outwardly beyond, asindicated in Figure 3, so that thereby the screen 16 is thoroughlycleaned.

In Figure 20 is shown the length of the pipe sections 120 comprising thenest of pipes 60, 61, 62, and '63 which extend upwardly from theoperating head or unit 18, said sections being connected by thecouplings 65. These pipe sections which constitute the principal lengthsof piping upwardly from the head may, in practice, he in theneighborhood of twenty-foot lengths. They are lowered into the well andcon nected until the operating head reaches to or about the level of thecompacted sand area A. Thereafter shorter pipe sections 121, shown inFigure 21, are successively attached totheupper ends of the pipesections, as the excavation of the compacted sand proceeds.

The sections 120 are placed in the well, by the use of the wheeled motorpropelled derrick 1) shown in Figure 2. Thereafter the shorter lengthsof pipes are added at .the top of the well by the use of an operatedlowering and raising device (see Figure 17) as the excavation throughthe sand proceeds.

The pipe sections and operating head are supported in the well while anadditional section is attached to the upper sections of pipe by theclamp 125 (Figures 17 and 19) said clamp comprising pivoted jaws 126,126 adapted to encircle the nest of pipes below the uppermost coupling65, 65, or 101 and adapted to be locked about the nest of pipes by theclasp 127. The clamp 125 rests on a plate 128 surrounding the top of thewell, and effectively holds the pipe lengths below and the operatinghead or unit when the piston stem 101 and the pipes 60 to 63, inclusive,are disconnected from the topmost coupling. After the operating head hasbeen lowered, through the proper number of sections 120 and theexcavation of the hardened sand proceeds,'the shorter pipe sections 121(which may preferably be of a length of four Or five feet) aresuccessively added at the top of the well, the operating head and theconnected sections being suplln ported by the clamp 125 during the timethe piston stem 101 and the pipes 60't0 63 inclusive, are disconnectedand until sai parts are again connected.

In applying the improved apparatus to a well to remove the compactedsand, the following procedure is generally observed:

The cap is removed from the well and a sounding tape is lowered into thewell to establishthe depth at which sand and other detritus is locatedand a note of this depth is taken. All lengths of pipe sections 120 and121 are labeled in numerical order, as, for instance, 1, 2, 3, etcetera, and when fastened together have a depth mark placed at eachpoint to show the exact length for connection to the point where theclamp 125 is fastened. The portable derrick D (Figure 2) is then movedabreast of the well and is blocked up in rear of rear axle and in aposition to bring the head sheave d of the head of derrick column d andan opening at bottom of derrick truck in line withthe well, the openingbeing guarded so as to keep the pipe section from covering it. Thederrick column d which, when not in op eration, lies horizontally alongthe bed of the truck is now raised to a vertical position and the headframe embodying the head sheave d placed thereon. The guys d, d are nowplaced to hold the column in vertical position.

Mounted beneath the truck bed on the chassis is a geared steel cablewinch d which is clutch connected to the engine of the derrick truck andso arranged that the drive to the rear axle can be cut out'and the winchcut in and operated from the seat of the truck. A cable from this winchis threaded through sheave d at the top of the derrick column and theapparatus is ready for lowering the sections in numerical order into thewell.

In thus lowering the sections in the well number 1 section, with itsoperative head placed thereon, is raised by the cable and winchmechanism to a vertical position and lowered in the well casing. Whenthis section is almost within the casing, the clamps 125 are clampedonto the upper end of the pipe secti on while the cable is disconnectedfrom the said section now placed. Thereafter section number 2 is liftedout of the truck and lowered in position and fastened to the sectionnumber 1 with the proper coupling, and the entire load of twosectionsoperation.

is now removed and the operating unit, shown in Figure 17, consisting ofthe lifting cylinder and its support is placed centrally above the wellcasing and the piston rod or stem 101 is connected to the upper coupling101". Thereafter the truck 78, together with the settling tank, the airtank, and compressor, is moved up in operative position to the cylinder100 and the coupling 101' and the pipe connections are made. with airand solvent supply and discharge. The air pump 85 is started untilsuflicient air pressure is obtained in the tank 85 for Thereafter ashort pipe section 121 is fastened to the piston rod of the air operatedreciprocating mechanism and connected with the last section of pipeplaced into the well casing. Air under sufficient pressure to raise theentire line and head is now admitted to the bottom side of the pistonthrough the valve 103 by removing pins 107 and manually operating thevalve, and the entire column in the well casing lifted so as to releasethe clamp 125. There after the column is slowly lowered into the well.Should this length of section be not sufficient to reach ,the sandlevel, other shorter sections must be attached and lowered until thelast section brings the excavator of the head in position to strike thesand level. Y

At this point of operation, the valve 62 is opened to admit air underpressure into turbine 45 and cause it to operate. The

61 to the top of the well and is discharged 7 on the plate 89 and thenceinto tank 80 (Figure 18). The sand and other detritus is now settled outand after the fluid has again risen to sufiicient height to flow intopipe 84 and thence to pipe 60 (Figure 18), it again returns to theoperative head or unit when the cycle is again repeated.

If the fluid head he too great for the pump to lift the solvent mixtureto the top of the well, the column of solution in the pipe 61 is boostedbv passing turbine exhaust air over to the pipe 61, either through thecrossover couplings described or otherwise. This air thus allowed toescape into the solvent discharge line serves to lighten the massspecific gravity of the solvent and its sand and detritus, so that thesolvent mixture may be pumped to a higher level than may be attained bythe pump 52, with a heavier fluid mass.

' When a solvent solution circulation has been attained it may beobserved flowing on plate 89 through sight glass 92. The link 108 is nowconnected at its upper end to the valve 103 and pin 107 inserted and thevalve 103" slowly opened so as to produce a very slow reciprocatingmotion to the entire col-' umn.

This column when slowly lowered causes the operating head 18 to begradually forced into the sand and detritus and the different lengthcutter vanes 27 and 28 and the pointed cutter 29 cause an easier cuttingoperation, and, in the event of hard sand, the point 29 prevents a toorapid entry of the cuttinghead. I

The sand, et cetera, which is thus removed is thrown upwardly and comesin contact with the rapidly agitated solvent and becomes very fineldivided and in good condition to be raise to the surface through themechanism already described.

When the sand is thoroughly pumped out this fact may be readily noted byobserving the character of the solvent through the sight 92 as it flowsover the plate 89 (Figure 18). When there is no more sand coming withthe solvent, the intake pipe from the solvent tank should be shut off bya proper valve and the solvent entirely pumped out and machine stoppedand another section of column 7 placed placed in the manner aspreviously described; the cycles of operation being repeated until thewell has been properly cleaned. When the screen level is attained, thereciprocation of the machine must be made to operate slower so as to notonly remove all sand and the like from the well casing, but from theholes in the screen and as far back from the screen as the power of theagitator 32 will cover, as shown in Figure 3.

I claim as my invention:

1. The method of cleaning obstructed oil Wells which comprises the stepsof delivering a hydrocarbon solvent of higher specific gravity thanwater to the compacted obstructive mass of the oil bearing stratum andthereafter raising the mixture of solvent and obstructive material tothe top of the well.

2. The method of cleaning obstructed oil wells, set forth in claim 1,characterized further in separating by filtration and gravity the solidmatter from the solvent and usin the solvent v over again.

3. The method of cleaning obstructed oil wells set forth in claim 1,characterized further in that the mass is mechanically broken upconcurrently with the delivery of the solvent above said broken mass.

4. The method of cleaning obstructed oil wells which consists in thesteps of excavating the obstructive mass, mixing a hydrocartiveiarticles.

bon solvent of higher specific gravity than water with the excavatedmass and thereafter raising the mixture of solvent andsolid obstructivearticles to the top of the well.

5. The method of cleaning obstructed oil wells set forth in claim 4,characterized further in that the solvent is violently mixed with andthrown radially into the obstruc- 6. he method of cleaning obstructedoil wells set forth in claim 1, and embracing the additionalstep ofmixing air or other fluid with the ascending mixture column at a pointwell above the mixture of said solvent and the particles of said mass.

7 7. The method of cleaning obstructed oil wells set forth in claim 1,and including the further step of injecting into the rising mixturecolumn at different stages a lighter fluid.

8. The method of cleaning obstructed oil well which comprises the stepsof excavating the obstructive mass at the casing screen, delivering ahydrocarbon solvent to said excavated mass, agitating the solvent in thepresence of the excavated obstructive mass and thereafter raising themixture of solvent and solid particles to the top of the well.

9. The method of cleaning obstructed oil wells which comprises the stepsof delivering a hydrocarbon solvent solution to the obstructive mass,dissolving thereby the binder by which the solid particles of theobstructive mass are bound together, raising the mixture of solventandsolid particles to the top of the well and directing lifting air intothe rising column of the mixture at vertically spaced stages.

10. The method of cleaning obstructed oil wells which comprises thesteps of delivering a hydrocarbon solvent solution to the compactedobstructive mass at the oil bearing stratum to dissolve the mass binder,

raising the mixture of the solvent solution and solid particles by theuse of a pump operated by an air-driven motor and delivering the air atvertically spaced stages along the column of the rising mixture ofsolvent and solid particles to assist in lifting said mixtures.

11. The method of cleaning obstructed oil wells which comprises thesteps of delivering a hydrocarbon solvent to the compacted obstructivemass, excavating the mass in the presence of said solvent, slowlyreciprocating the excavating mechanism towards and from the obstructedmass during the operation of the excavator, and raising the mixture ofthe solvent solution and the solid particles of the excavated mass tothe top of the well.

12. Mechanism for cleaning obstructed oil wells comprising an excavatingdevice for attacking the obstructive mass inthe well a motor to drivethe same, means for delivering .a solvent to the well casing at thelevel of its screen and forcibly outwardly therebeyond to dissolve thebinder element of the solid obstructive mass, and means for raising themixture of the solvent and solid particles of the obstructive mass.

13. 'Mechanism for cleaning obstructed oil wells comp-rising means todeliver a solvent to the level of the obstructive mass in the well todissolve the binder of said mass,

means to agitate solvent solution at said mass and to throw it radiallybeyond the well screen into the obstructive mass therebeyond, and meansto raise the mixture of solvent solution and solid particles of saidmass.

14. Mechanism for cleaning obstructed oil wells comprising means todeliver asolvent to the level of the obstructive mass in the well todissolve the binder of said mass, means to agitate the solvent solutionat said mass and to throw the solvent radially beyond the well'casingscreen, and means to raise the mixture of solvent solution and solidparticles of said mass, combined with means for admitting to the risingmixture column fluid of lesser specific gravity.

15. Mechanism: for cleaning obstructed oil wells comprising means todeliver a solvent to the level of the obstructive mass in the well todissolve the binder of said mass and the binder of the mass radiallyoutwardly beyond the well casing screen, means to agitate solventsolution at said mass, and means to raise the mixture of said mass,combined.

with means for admitting to the rising mixture column at difl'erentelevations boosting fluid of lesser specific gravity.

16. Mechanism for cleaning .obstructed oil wells comprising an operatinghead which embraces an excavating device for attacking the obstructivemass at the bottom of the well casing, an agitator immediately above theexcavator for mixing the excavated material with a liquid solvent, andmeans for delivering a liquid solvent to the agitator to be therebythrown outwardly against the excavated material.

17. Mechanism for cleaning obstructed oil wells comprising an operatinghead which embraces an excavating device for attacking the obstructivemass at the bottom of the well casing, an agitator immediately above theexcavator for mixing the excavated material with a liquid solvent,

means for delivering a liquid solvent to the agitator to be therebythrown outwardly against the excavated material, a'motor in said headfor driving said excavating device, and a pump also in said head forraising the mixture of the fluid solvent and solid matter to the top ofthe well.

18. In a mechanism for cleaning obstructed oil wells, an excavator forattacking the obstructive-mass, comprising upper and lower transverselyspiral cutting blades, the lower blades being shorter than the upperblades, and a restricting and guiding point.

19. Mechanism for cleaning obstructed oil wells comprising anoperatinghead which embraces an excavating device formed with longer upper andshorter lower operable blades, a directing point, an agitator above theexcavator, means to deliver liquid solvent to the agitator, and means toraise the mixture of solvent and the agitated mixture.

20. Mechanism for cleaning obstructed oil wells comprising an operatinghead embracing an enclosed fluid proof shell adapted to be inserted intothe well casing at the screen level, an excavator carried by said head,a motor withinthe head for driving the excavator, an agitator driven bysaid motor near the level of the excavator, means for delivering asolvent below the casing atthe level of the agitator, and means for raising the mingled solvent and solid particles to the top of the well.

21. Mechanism for cleaning obstructed oil wells comprising an operatinghead embracing an enclosed fluid proof shell adapted to be inserted intothe well casing at the screen level, an excavator carried by said head,a motor within the head for driving the excavator, an agitator driven bysaid motor near the level of the excavator, means for delivering asolvent below the casing at the level' of the agitator, a centrifugalpump at the top of and enclosed by said casing for raising the mixtureof the solvent solution and solid obstructive particles to the top ofthe well, and means within the head for driving said pump from themotor.

22. Mechanism for cleaning obstructed oil wells comprising an operatinghead embracing an enclosed fluid proof shell adapted to be inserted intothe well casing at the screen level, an excavator carried by said head,a motor within the head for drivingthe excavator, an agitator driven bysaid motor near the level of the excavator, means for delivering asolvent below the casing at the level of the agitator, a centrifugalpump at the top of and enclosed by said casing for raising the mixtureof the solvent solution and solid obstructive particles to the top ofthe Well, means for driving said pump from the motor, said motor beingan air driven motor, and means for directing the exhaust air from saidmotor to the column of rising mixture at vertically spaced stages.

23. Mechanism for cleaning obstructed oil wells comprising an operatinghead embracing an enclosed fluid shell adapted to be inserted into thewell casing at the screen level, an excavator carried by said head, anagitator near the level of the excavator, a motor within the head gearedto the excavator and agitator to drive the latto connect said pump tosaid motor to drive tel, means for delivering a solvent below it at highspeed relatively to the speed of the casing at the level of theagitator, a the agitator and agitator excavator. 10 centrifugal pump atthe top of and en- In witness whereof I claim the foregoing 5 closed bysaid casing for raising the mixture as my invention, 1 hereunto appendmy of the solvent solution and solid obstructive signature this 19th dayof December 1919. particles to the top of the Well, and means FRANKLINH. VOLEVICR.

